Use of salts of readily decarboxylated acids in thermography, photography, photothermography and thermophotography



Nov. 30, 1965 J. F. TINKER ETAL USE OF SALTS 0F READILY DECARBOXYLATED ACIDS I THERMOGRAPHY, PHOTOGRAPHY, PHOTOTHERMOGRAPHY AND THERMOPHOTOGRAPHY Filed June 27, 1960 2 Sheets-Sheet l THERMOSRAPHIC LAYER CONTAIN/N6 2,3 omzmvweuzommzoum-P I TOLUENESULFO/VATE,

,p QU/NONE AND PIPERIDINIUM TRICHLOROACETATE SUPPORT Fig:1A 14 w LAMP l l I I l POSITIVE RECORD M \JTHERMOGRAPHIC LAYER SUPPORT PRINTED CHARACTER ORIGINAL Figzz 19 LIGHT SOURCE ORIGINAL. IMAGE Pl-IUTOTHERMOGRAPH/C LAYER CONTAINING 4-DIETHYLAMINOBENZENEDIAZONIUM CHLORIDE ZINC CHLORIDE,

.3 -DIHYDROXYNAPHTHALENE AND 2 \MORPHOIJNIUM TRICHLOROALETATE S U PP 0 RT POSITIVE RECORD L\PH0T0THERM06RAPHIC LAYER '\SUPPORT John J: Sagura John/R Tinker IN VEN TORS' BY%M,M

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ATTORNEY & AGEIVI' 3 1965 J. F. TINKER ETAL 3,220,845

USE OF SALTS OF READILY DECARBOXYLATED ACIDS IN THERMQGRAPHY, PHOTOGRAPHY, PHOTQTHERMOGRAPHY AND THERMOPHOTOGRAPHY Filed June 27, 1960 2 Sheets-Sheet 2 Figz3 INFRA-RED LAMP -THERMOPHOTOGRAPHIC LAYER CONTAINING 4-DIETI-IflAM/NOBBVZEVEDIAZONIUM CHLORIDE ZINC CLORIDE 2,3 'DIH YDROX YNAPH THALE NE AND yORPHOLINIUM TRICHLOROACE'MTE s (J P P OR 7' ORIGINAL PRINTED CHARACTER /-THERMOPHOTOGRHPHIC LAYER CONTAINING 4-DIE THYLA MIN 0 BflVZBVED/AZON/l/M CHLORIDE ZINC CHLORIDE,

2,3 *D/HYDROXWVAPHTHALENE AND MORPHOLINIUM TRICHLOROACETATE S UPPOR T '9 \LIGHT SOURCE 17 ,8 ORIGINAL IMAGE LI6HT-SENSITIVE SILVER HALIDE EMULSION LAYER CONTAINING g4 F "AM/NOPHENOL TRICHLOROACEMTE SUPPORT Fi 9: 4A

SUPPLY OF STEAM 25 STEAM CHEST POSITIVE RECORD 24 suPPoR-r John J: Sagura/ J ohnE Tinker IN VEN TORS' IEZTORNBY & AGENT United States Patent USE OF SALTS 0F READILY DECARBOXYLATED ACIDS IN THERMUGRAPHY, PHOTOGRAPHY, PHOTOTHERMBGRAPHY AND THERMOPHG- TOGRAPHY John F. Tinker and John J. Sagura, Rochester, N.Y., as-

signors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed June 27, 1960, SeraNo. 39,155 11 Claims. (CI. 96-91) This invention relates to the use of heat-sensitive salts of readily decarboxylated organic acids in heat-sensitive elements for thermography, photothermography, thermophotography and photography.

Thermographic, photothermographic and thermophotographic copying materials and methods have been previously described in a number of domestic and foreign patents. The use of light-sensitive silver halide emulsion layers which incorporate a developing agent and in which the latent image may be developed by heat processing have been described in patents. These materials usually have the advantage over other copying materials of being processed simply and rapidly without use of solutions, to give direct positive images. For example, thermographic materials are used to produce copies by holding the support of the thermographic copying material in conductive contact with the original image, while passing infrared radiation through the copying material, thus creating a heat pattern of the image in the original which is conducted to the heat-sensitive layer of the copying material where a corresponding image is produced. Photothermographic copying materials are exposed through an image transparency with visible light to differentially photodecompose the light-sensitive component in areas of the copying material corresponding to the transmitting areas of the transparency and then a visible image is formed in the copying material by heat treatment. Thermophotographic copy material is exposed in the same manner as the thermographic material and the image produced is stabilized by photodecomposition of the residual unreacted light-sensitive component in the image layer.

Certain of these thermographic, photothermographic and thermophotographic copying materials used previously are not as sensitive as desired, and, consequently, require relatively long exposure to produce a facsimile copy. Other materials may not sutfer from the aforementioned limitation, but they are difficult to use or handle because they contain metallic ions which might stain the support uopn which the heat-sensitive layer is coated. Other materials exhibit thermotrophy and loss in developed color when the heat-sensitive material is cooled to room temperature.

It is, therefore, an object of our invention to provide novel thermographic, photothermographic and thermophotographic copying materials which have improved sensitivity, which are free of stain problems, and which produce images that are stable.

A further object is to provide valuable thermographic, photothermographic and thermophotographic copying materials which contain salts of readily decarboxylated organic acids which, upon heating, release in situ basic materials such as amines, reducing agents, such as photographic developing agents, catalysts or color-forming compounds which react with other components present or which bring about chemical reactions between other components present to create the visible image.

A further object is to provide a light-sensitive silver halide emulsion which contains a heat-sensitive salt of a readily decarboxylated organic acid and a reducing agent which, upon exposure, becomes developable by heat treat- 3,22%,846 Patented Nov. 30, 1965 ice ment which produces in situ a reducing agent that develops the exposed silver halide to a silver image.

Other objects will become apparent from the following specification and claims.

We have discovered that these and other objects are accomplished by incorporating heat-sensitive salts of readily decarboxylated organic acids in radiant energy sensitive layers used for thermography, photothermography, therrnophotography and photography. The heatsensitive salts of readily decarboxylated organic acids which are valuable for use in our invention are represented by the formula:

in which WH+ represents a member selected from the class consisting of:

radical, and a (NH C=NHH+ radical in which L represents the non-metallic atoms necessary to complete a cyclic structure such as a piperidine radical, a Z-alkyl or 4-alkyl substituted piperidine radical in which the alkyl radical has from 1 to 8 carbon atoms, e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tertiarybutyl, n-amyl, isoamyl, hexyl, heptyl, octyl, etc., such that the piperidine radical may be Z-methylpiperidine, 4- ethylpiperidine, 2-propylpiperidine, 4-isopropylpiperidine, 2-butylpiperidine, 4-isobutylpiperidine, Z-tertiarybutylpiperidine, 4-isoamylpiperidine, 2-hexylpiperidine, 4-octylpiperidine, etc., a Z-alkarylpiperidine in which the alkaryl group has from 7 to 14 carbon atoms, e.g., methylphenyl, ethylphenyl, propylphenyl, butylphenyl, amylphenyl, hexylphenyl, heptylphenyl, octylphenyl, etc., 2[2,4-dinitrobenzyl] pyridine, etc., morpholine, a 2-alkrnorpholine in which the alkyl group has from 1 to 8 carbon atoms, such as defined above and in which the Z-alkyl morpholine radical may be 2-methylmorpholine, 2-propylmorpholine, 2-hexylmorpholine, 2-octylmorpholine, etc., 2-alkarylmorpholine radicals in which the alkaryl has from 7 to 14 carbons atoms as defined above and the 2-alkarylmorpholine radical may be a radical, such as Z-methylphenylmorpholine, 2-butylphenylmorpholine, 2 octylphenylmorpholine, etc.; R represents a hydrogen atom, a lower alkyl of from 1 to 4 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tertiarybutyl, etc.; d is a positive integer of 1 to 2; X represents a hydrogen atom, a hydroxyl group or a dialkylamine radical in which the alkyl groups each have from 1 to 4 carbon atoms as defined above; R represents a hydrogen atom, an alkyl radical having from 1 to 8 carbon atoms as defined above, aminoalkyl radicals, such as aminomethyl, aminoethyl, etc; R represents an aminoalkyl radical as defined above or a 1,3-dihydroxy-2-hydroxymethyl-2-propyl radical; n is the positive integer 1, 2 or 3; Y represents a hydrogen atom, a chlorine atom, a bromine atom of a fluorine atom; in is the positive integer 1, 2, 3 or 4; and Z represents a radical, a CI C radical, a F C radical, a Br C radical, a NC- radical or a (NO C radical.

\Vhen the heat-sensitive salt compounds of our invention are heated to the temperature at which the acid moiety decarboxylates, there is produced a free'base represented by W of the formula, CO and a compound having the formula H[CY Z. For example, when piperidine trichloroacetate, one of the salts of our invention, is heated to the decarboxylation temperature, piperidine, carbon dioxide and chloroform are produced.

The following compounds are representative of the heat-sensitive salts of readily decarboxylated acids of our invention. (1) Piperidinium trichloroacetate (2) Morpholinium trichloroacetate (3) 2-pico1ine trichloroacetate l EEO-: C Ola (4) 1-methyl-2(2,4-dinitrobenzyl)pyridinium trichloroacetate Cfia H+o-,o O on (5 Guanidinium tricholoroacetate =NH+,0:C o 013 (6) Tetraethylammonium trichloroacetate H C -NC+ H 0-;C C on (7) Triethylenediamine trichloroacetate (HgNCHzCHflaNBH'OgC o 013 8 l,3-dihydroxy-2'hydroxymethyl-2-propylammonium trifluoroacetate 4 (10) 1,3-dihydroxy2-hydroxymethyl-2-propylammonium trichloroacetate OH (1H, HOOH2-NH2-HO2CCC1 (1 l) p-Toluidinium trifiuoroacetate I IHg-HO CCF (12) 2-amino-5-diethylaminotoluene trichlor-oacetate NHz-HOgCCCl (l3) p-Aminophenol trifiuoroacetate I IHg-HOzCCF 14) p-Methylaminophenol trichloroacetate In general, the amine salt compounds are prepared by adding a solution of the base, compound W, dissolved in a suitable solvent, such as diethyl ether, to a solution of the acid,

dissolved in the same solvent or a compatible solvent. The salt compound precipitates, is removed by filtration, washed with solvent to remove excess reactants, filtered and dried in a vacuum desiccator.

The preparation of piperidine trichloroacetate will further illustrate this process.

EXAMPLE I 1.0 mole of piperidine dissolved in 150 cc. of diethyl ether was added to a solution of 1.1 moles of tn'chloroacetic acid dissolved in cc. of diethyl ether. The precipitated salt, piperidine trichloroacetate was collected, filtered, washed with cc. of diethyl ether, filtered and dried in a vacuum desiccator.

We have found that it is advantageous to use mixed salts having a common acid moiety, such as a mixture of piperidinium trichloroacetate and morpholinium trichloroacetate. The following example illustrates how such a mixture was prepared.

EXAMPLE II The process of Example I was used, but an ether solution containing 0.9 mole of piperidine and 0.1 mole of morpholine was added to the ether solution containing 1.1 moles of trichloroacetic acid. The resulting mixture of piperidinium trichloroacetate and morpholinium trichloroe acetate was purified and dried as in Example I.

In general, the quaternary ammonium salt compounds are prepared by adding an alcohol solution of the quaternary ammonium chloride salt to an alcohol solution of the sodium salt of the appropriate acid. The precipitated sodium chloride is then removed by filtration and the quarternary salt product is isolated from the filtrate either by evaporation of the solvent or precipitation with a nonsolvent. If the desired quarternary salt is insoluble in water, aqueous solutions may be employed. The product then precipitates from the reaction mixture.

The preparation of 1-methyl-2(Z-dinitrobenzyl) pyridinium trichloroacetate will illustrate this type of reaction.

EXAMPLE III 1 methyl 2[2,4 dinitrobenzylJpyridinium trichloroacetate was prepared as follows:

Equimolar amounts of l-methyl-Z[2,4-dinitrobenzyl] pyridinium chloride and sodium trichloroacetate were dissolved in a minimum of absolute ethanol. The solution was stirred at 50 C. for four hours, the precipitated sodium chloride was filtered off and the filtrate was evaporated to dryness. The product was purified by solution in absolute ethanol followed by precipitation with diethyl ether.

EXAMPLE IV Guanidinium trichloroacetate was prepared as follows:

Ninety grams (0.5 mole) of guanidine carbonate was placed in a one-liter Erlenmeyer andcovered with methanol (150 cc.). To this was added slowly a solution of 245.1 grams (1.5 moles) of trichloroacetic acid in 150 cc. of methanol. After the addition was completed, the reaction mixture was warmed on the steam bath with the addition of more methanol (approx. 200 cc.) until all the guanidine carbonate was in solution. This was allowed to cool in the ice chest and filtered. The filtrate was evaporated to about one-third of its original volume on a Rinco evaporator, cooled and filtered. The filtrate was then diluted with ether and filtered. The three crops of the crystalline product were combined and recrystallized from methanol, yield 114 grams (51.5 percent of theoretical), MP. 162l63, M.W. 222.

EXAMPLE V The other heat-sensitive salts of our invention were prepared by one of the methods illustrated above. Table I lists the base or salt, the acid or sodium salt, and the solvent used in the preparation of the representative examples of our heat-sensitive salt.

Table I Salt Com- Base (or salt) Acid (or sodium salt) Solvent pound Pipcridine Trichloroacetie acid--. Diethyl ether. Morpholine .do D0. 2-pinnline n D 1-rnethyl-2(2,4-diui- Sodium trichloro- Ethanol.

trobcnzyl) p yridinacetate. ium chloride. 5 Guanidine carbonate.-- do Methanol. 6 Tetraethylemmon- Sodium trichloro- Water.

ium chloride. acetate. 7 Tricthylene-diamiue. Trichloroacetic acid-.- Methanol. 8 1,3-dihydroxy 2- Trifluoroacetic acid. D0.

hydroxymcthyl-2- propylamine. 9 "do Perfluorobuterlc acid Diethyl ether. 10 do Trichloroacetic acid Do. 11 p-Toluidine Tritluoroacetic acid- Methanol. 1.. 2-amino-5-diethyl- Trichloroacetic acid.-. Diethyl amino-toluene. ether. 13 p-Aminophenol Trifiuoroacetic acid Methanol. 14 p-MethylaminophenoL Trichlotoacctic acid--- Do.

. polyvinyl acetal, ethyl cellulose, methyl cellulose, polyvinyl acetate or any other water or alcohol-soluble polymer is used. These layers are coated upon paper or other fibrous compositions which have a char temperature that is preferably above C. These layers may also be coated on transparent materials used for photographic film base such as cellulose acetate, polyethylene terephthalate, polystyrene, polycarbonates, etc.

Heat-sensitive copying material of the thermographic type which contains our heat-sensitive salts have (a) a component such as a heterocyclic quaternary salt having the formula (II) Q an ll I "-o\ 23-12 6? in J in which D represents the nonmetallic atoms necessary to complete an aromatic ring, a heterocyclic ring or a carbocyclic ring, Q represents a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, or a (CH): group, 1 represents 0 or 1, R represents an alkyl group having from 1 to 18 carbon atoms or an aryl group, R represents an alkyl group having from 1 to 18 carbon atoms or an aralkyl group, J represents an acid anion of an acid weaker than the readily decarboxylated acid of Formula I, such as p-toluenesulfonate, methyl sulfate, alkylsulfonate, chloroacetate ions, etc., such that the quaternary ammonium salt may be a benzothiazolium salt compound, for example, 2,3-dimethylbenzothiazolium p-toluenesulfate, 2,3-dimethyl-S-alkylbenzothiazolium ptoluenesulfonate, in which the alkyl group may have from 1 to 8 carbon atoms, e.g. methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, etc., 2,3-dimethyl-6-alkylbenzothiazolium p-toluenesulfonate in which the alkyl group may have from 1 t0 8 carbon atoms as defined above, 1,4 dimethylquinolinium p toluenesulfonate, 1- ethyl-Z-picolinuim p-toluenesulfonate, 3-ethyl-2-methylbenzothiazolium p toluenesulfonate, a benzoxazolium compound e.g. 2,3-dimethylbenzoxazolium salt compound, e.g. 2,B-dimethylbenzoxazolium p-toluenesulfonate, 2,3- dimethyl 5 alkylbenzoxazolium p toluenesultonate in which the alkyl group may have from 1 to 8 carbon atoms as defined above, and (b) a p-quinone or a subr stituted p-quinone which has at least one unsubstituted hydrogen on the ring such as the p-quinones of Crevling et al., US. Patent 2,899,334 issued August ll, 1959, or alternatively, cupric salts such as cupric chloride, cupric chloride dihpdrate, cupric nitrate, cupric nitrate trihy; drate, cupric nitrate hexahydrate, cupric sulfate, cupric sulfate pentahydrate, etc.

Copying materials of the photothermographic and thermophotographic type containing our heat-sensitive salts also contain (a) a radiant energy sensitive component, e.g., a diazonium compound of the type conventionally used in the art of diazophotography along with one or more conventional diazo-couplers.

Light-sensitive silver halide photographic copying materials of our invention contain heat-sensitive salts which, upon decarboxylation, produce free developing agents, such as p-aminophenol, 2-amino-S-diethylaminotoluene, p-methylaminophenol, etc. They may also contain a second heat-sensitive salt of our invention which, upon decarboxylation, releases a basic material such as piperidine, morpholine, 2-pico1ine, guanidine, etc.

The following examples will illustrate specifically representative applications of our salts in these heat-sensitive copying materials.

EXAMPLE VI A thermographic copying material was prepared as follows:

The methanolic solution of poly(vinylbutal), 2,3-dimethylbenzothiazoliurn p-toluenesultonate, p-quinone and piperidinium trichloroacetate was coated on a thin paper base. After drying, the suport of this copying material was held in conductive relationship with a printed original and infra-red radiation was passed through the copying material. This created a heat pattern according to the image of the printed original which was conducted through the support of the copying material and created a corresponding visible image in the heat-sensitive layer.

Alternatively, the dry thermographic copying material may be exposed to infra-red radiation by passing the radiation through the printed original instead of passing it through the copying material as described above. In order that this be possible, however, the support of the printed original must be capable of transmitting infrared radiation.

In this process, the piperidinium trichloroacetate decarboxylated in the areas corresponding to the heat image produced in the original to release piperidine in situ and thus causing the 2,3-dimethylbenzothiazolium p-toluenesulfonate to couple with the p-quinone to produce a dye image.

Although any of the base releasing heat sensitive salts of our invention may be used for the thermographic type of copying material, we have found that those having decarboxylation temperatures in the range of 60 C. to 130 C. are to be preferred.

We have discovered that the stability of heat-sensitive copying materials during the period of storage before exposure and use, can be improved appreciably by the use of mixtures of two heat-sensitive salts having a common acid moiety in place of a single heat-sensitive salt. For this reason, it is particularly advantageous to use such mixtures especially Where the heat-sensitive salt has a relatively low decarboxylation temperature.

Examples VII and VIII serve to illustrate this eifect.

EXAMPLE VII An ether solution of 0.9 mole of piperidine and 0.19 mole of morpholine was added to an ether solution of 1.1 mole of trichloroacetic acid. The precipitated solid was collected, dried in a vacuum desiccator and stored in a closed bottle. A sample of piperidinium trichloroacetate was prepared and stored in a similar manner. After one week, the stored sample of piperidinum trichloroacetate had decomposed, while the mixed salt sample showed no signs of decomposition even after one month. A sample of the mixed salt exposed to the atmosphere also showed no signs of decomposition after one month.

EXAMPLE VIII Guanidinium trichloroacetate (decomposes at 162 C.) was mixed intimately with l-methyl-Z[2,4-dinitrobenzyl] pyridinium p-toluenesulfonate (decomposes at 200 C.). A sample of this mixture began to turn blue (the characteristic color of the anhydro base of the pyridinium salt) at 65 C. A coating, on paper, of a dope containing 1 gram of the guanidinium salt and /2 gram of the pyridinium salt in 100 millimeters of 10% gelatin was dried and exposed in contact with a printing original and exposed to infra-red radiation in the manner described in Example 6, such that the image temperature was 100 C. An excellent blue image resulted.

Valuable thermographic copying material is made in which the p-quinone compound is replaced by a cupric salt. We have found that in general the exact stoichiometry for a thermographic layer containing such a salt combination must be determined empirically. We have also found that those quaternary salts of Formula II in which the R bears an active hydrogen atom are most useful in thermographic layers and the operating temperature of the layer may be varied by varying the concentrations of the salts employed or by adding a common anion or a foreign anion to the system. Common ions tend to raise the operating temperature while foreign ions tend to lower the operating temperature.

In practice, a coating on a suitable support is made salt in the exposed areas.

from a solution of the indicated materials in the empirically determined stoichiometric amounts and a resinous binder in a common solvent. The coating is then exposed by the procedure used in Example 6 to create a visible image in the heat-sensitive layer. The color and stability of the colored image formed can be varied by the particular salt combination employed. The background color is uniform in color and density and is not to be confused with the mottled or streaked stains that develop in some prior art elements containing metallic The following Examples 9, 10, and 11 illustrate typical embodiments of this system.

EXAMPLE IX A solution in 50 ml. of methanol of 3.43 grams of 1,4-dimethyl quinolinium p-toluenesulfonate, 2.2 grams of guanidinium trichloroacetate and 0.85 gram of cupric chloride dihydrate was added to 50 ml. of a 5 percent solution of ethyl cellulose (such as Ethocell T-l00 made by Dow Chemical Company), in 9:1 ethanol-benzene. The resulting dope was coated on the sized side of Rhinelander Opaque Greaseproof paper. Exposure of the coated element according to the method used in Example 6 gave a blue image on a pale yellow background.

EXAMPLE X A solution of 50 ml. of methanol of 3.5 grams of 3- ethyl-Z-methylbenzothiazolium p-toluenesulfonate, 2.2; grams of guanidinium trichloroacetate and 0.85 gram of cupric chloride dihydrate was added to 50 ml. of a 5 percent solution of ethyl cellulose in 9:1 ethanol-benzene. The resulting dope was coated on the sized side of Rhinelander Opaque Greaseproof paper. Exposure by the method described in Example 6 produced an excellent blue image on a pale yellow background.

EXAMPLE XI A solution of 50 ml. of methanol of 3.5 grams of 3-ethyl-Z-methylbenzothiazolium p-toluenesulfonate, 2.2 grams of guanidinium trichloroacetate and 0.36 gram of cupric nitrate trihydrate was added to 50 ml. of a 5 percent solution of ethyl cellulose in 9:1 ethanol-benzene. The resulting dope was coated on the sized side of Rhinelander Opaque Greaseproof paper. Exposure by the procedure used in Example 6 produced an excellent blue image on a white background.

EXAMPLE XII A photothermographic copying material was prepared as follows:

A methanolic solution of p0ly(vinylbutal), 4-diethylaminobenzenediazonium chloride zinc chloride, 2,3-dihydroxynaphthalene and piperidinium trichloroacetate was coated on a film base. The dry coating was exposed through a continuous tone positive transparency to a General Electric R.S. Reflector Sunlamp at 10 inches for one minute to differentially destroy the diazonium The exposed plate was then heated at C. for 30 seconds to liberate the piperidine from its salt to develop the positive violet azo dye image. Alternatively, daylight or any other approximation of daylight can be used in place of the General Electric R.S. Reflector Sunlamp used to differentially destroy the diazonium salt in the exposed areas of the photothermographic copying materials of our invention.

Although any of the heat-sensitive salts of our invention which release a basic material upon decarboxylation, may be used for photot-hermographic copying materials, we have found that those having a decarboxylation temperature of from 100 C. to C. are to be preferred for this application.

The following example will illustrate how our heatsensitive salts are used in copying materials for thermophotography.

9 EXAMPLE XIII A thin paper base was coated With the composition described in Example XII and the coating was allowed to dry. The dry copying material was then exposed in contact with a printed original by the method described in Example VI. The print was then exposed to a General Electric RS. Sunlamp for 30 seconds to destroy the residual diazonium salt and thus stabilize the print.

The following example will illustrate how the heatsensitive salts of our invention that have a reducing agent as the basic moiety of the salt are used in light-sensitive silver halide emulsions for photography.

EXAMPLE XIV A sheet of silver bromide paper, such as Kodabromide E-S, was soaked in a dilute aqueous solution of the trifluoroacetic acid salt of p-aminophenol for 30 seconds and then allowed to dry. The dry copying material was then exposed through a negative pattern with a 60-watt incandescent lamp at 2 feet for 60 seconds. The emulsion side of the paper was then steamed for 30 seconds to develop a blue-brown positive image. Untreated silver bromide paper of the same type subjected to the same treatment gave no image.

Similarly, other photographic printing paper may be treated in dilute aqueous solutions of heat-sensitive salts of our invention containing other developing or reducing agents to produce similar results.

Heat-sensitive salts of readily decarboxylated acids can also be made of other compounds which, when freed from the salt by decarboxylation of the acid moiety, are useful in copying materials and in photography. For example, such salts may be made which generate catalysts, such as mercury and mercuric ions, stabilizing materials, such as antifoggants, e.g., a merc-aptotetrazole, color-forming compounds, such as illustrated above and other types of reactants commonly used in photography.

The accompanying drawings, FIGURES 1, 1A, 2, 2A, 3, 3A, 4 and 4A, further illustrate how our heat-sensitive decarboxylatable salt compounds are used in copying elements and how these elements are used.

FIGURE 1 represents a cross sectional view of a thermographic element consisting of a support and thermographic layer 11 containing 2,3-dimethylbenzothiazolium p toluenesulfonate, p quinone and piperidinium trichloroacetate.

FIGURE 1A illustrates how the printed character 12 of the original 13 is copied in thermographic layer 11 by passing infra-red radiation from infra-red lamp 14 through the thermographic layer 11 and support 10 held in conductive contact with the original printed character 12, thus creating a heat pattern of 12 that is conducted through the support 10 resulting in the production of piperidine in 11 from decarboxylation of piperidine trichloroacetate according to the heat pattern, followed by the color-forming reaction of 2,3-dimethylbenzothia zolium-p-toluenesulfonate with p-quinone where piperidine was produced.

FIGURE 2 shows a cross sectional view of a photothermographic element consisting of a support 15 coated with a photothermographic layer 16 containing 4-diethylamino-benzenediadonium chloride zinc chloride, 2,3-dihydroxynaphthalene and morpholinium trichloroacetate which is being exposed by light from 19 through image 17 in original 18 to photodecompose the 4-diethylaminobenzenediazonium chloride in layer 16 excepting under image 17.

FIGURE 2A shows the heat processing of the exposed layer 16 by exposure to infra-red radiation from 14 to produce morpholine by decarboxylation of morpholinium trichloroacetate which causes the invisible 4 diethylaminobenzenediazonium chloride zinc chloride image to react with 2,3-dihydroxynaphthalene to produce a visible positive record of the original.

' FIGURE 3 shows a cross sectional view of a thermophotographic element consisting of support 22 coated with a thermophotographic layer 21 containing 4-diethyl- 'aminobenzenediazonium chloride zinc chloride, 2-3-dihydroxynaphthalene and morpholinium trichloroacetate which is being exposed to infra-red radiation from 14 while support 22 is held in conductive cont act with image 12 in original 13. The heat pattern formed of image 12 is conducted through 22 and produces morpholine by decarboxylation of morpholinium trichloroacetate in the areas corresponding to the heat pattern where a visible image-forming reaction occurs between the 4-diethylaminobenzenediazonium chloride and the 2,3-dihydroxynaphthalene to produce positive record image 20.

FIGURE 3A shows how visible image 20 is stabilized by exposing layer 21 to light source 19 to photodecompose the residual 4-diethy-laminobenzenediazonium chloride in layer 21.

FIGURE 4 represents a cross sectional view of a photographic element consisting of support 24 hearing lightsensitive silver halide emulsion layer 23 containing incorporated p-aminophenol trichloroacetate which is being exposed to light from 19 through image 17 in original 18.

FIGURE 4A shows the heat processing of the exposed element of FIGURE 4 by exposing layer 23 to steam which causes the p-aminophenol trichloroacetate to decarboxylate with the release of p-aminophenol which develops the exposed silver halide to form the silver positive record 25.

The novel heat-sensitive copying materials of our invention are characterized by containing heat-sensitive salts of readily decarboxylated organic acids. We have found that it is highly advantageous to use a mixture of two heat-sensitive salts which have a common, readily decarboxylated organic acid moiety. This improves the stability of the unused copying material during storage periods. These copying materials are prepared for thermographic, photothermographic, thermophotographic methods or for silver halide photographic methods. Upon heat processing of these materials, the incorporated heat-sensitive salt decarboxylates and produces in situ the basic moiety of the salt which may be a reducing agent, such as a photographic developer that brings about the development of exposed silver halide, a basic material which causes the reaction of other components present, such as the coupling reaction of the 2,3-dimethylbenzothiazolium p-toluenesulfonate and p-quinone as illustrated in Example VI or the reaction of 1,4-dimethylquinolinium-p-toluenesulfonate and cupric chloride dihydrate as illustrated in Example IX. The novel heatsensitive copying materials of our invention are valuable because they may be quickly and conveniently processed to form a stable and permanent image which is not subject to stain problems as are common with some of the prior art copying materials. Furthermore, the heat sensitivity of compounds used in our copying materials is such that they require relatively short exposure and heat treatment to produce a good facsimile reproduction.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be eifected within the spirit and scope of the invention as described hereinabove and :as defined in the appended claims.

We claim:

1. A heat processable radiant-energy-sensitive imageforming layer containing:

(A) a heat-sensitive salt compound of a readily decarboxylatable compound being selected from those having the formula:

ll wherein WH+ represents a member selected from the class consisting of:

radical and (NH C=NHH+ radical in which L represents the nonmetallic atoms necessary to complete a cyclic structure selected from the class con sisting of piperidine, 2-alkyl substituted piperidine, picoline, 2-a-lkyl substituted pyridine, and morpholine; R represents a member selected from the class consisting of a hydrogen atom, a lower alkyl radical having from 1 to 4 carbon atoms; d is an integer of from 1 to 2; X represents a member selected from the class consisting of a hydroxyl radical, and an -NR radical; R represents a member selected from the class consisting of a hydrogen atom, an alkyl radical having from 1 to 8 carbon atoms, an aminoalkyl radical having from 1 to 6 carbon atoms; R represents a member selected from the class consisting of a 1,3-dihydroxy-2-hydroxymethyl-Z-propyl radical and an aminoalkyl radical having from 1 to 6 carbon atoms; n is an integer of from 1 to 3; Y represents a member selected from the class consisting of a hydrogen atom, a chlorine atom, a bromine atom, and a fluorine atom; m is an integer of from 1 to 4; and Z represents a member selected from the class consisting of a radical, a Cl C radical, a F C radical, a I C radical, a Br C radical, a NEC- radical, and a (NO C radical, such that when Z is a 0 CH3(I' radical, in is the integer 2 and Y is a hydrogen atom, said organic acid moiety of said salt compound decarboxylating upon heating to release a free amine selected from the class consisting of those having the formulas:

1* r K R N, and H:NCNH:

i R R! wherein L, R, R, R and X are as defined previously, and (B) at least one radiant-energy-sensitive image-forming composition selected from the class consisting of: (1) a heterocyclic quaternary salt selected from those having the formula:

in I

wherein D represents the nonmetallic atoms necessary to complete a ring selected from the class consisting of a heterocyclic ring and a carbocyclic ring; Q represents a group selected from the class consisting of nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom and a. (CH): group; p represents an integer from 1 to 2; R represents a group selected from the class consisting of an alkyl group having from 1 to 18 carbon atoms and an aryl group, R represents a group selected from the class consisting of an alkyl group having from 1 to 18 carbon atoms and an aralkyl group; J represents an anion selected from the class consisting of a ptoluenesulfonate ion, a lower alkylsulfonate ion and a'chloroacetate ion; and a p-quinone having at least one unsubstituted hydrogen atom on the (2) said heterocyclic quaternary salt and a cupric salt;

(3) a diazonium compound and a diazo-coupler;

(4) a light-sensitive silver halide and a silver halide developing agent; and

(5) a light-sensitive silver halide and a heat-sensitive salt of a primary amino silver halide developing agent and a readily decarboxylatable organic acid.

2. A heat processable radiant-energy-sensitive imageforming layer of claim 1 which has a hydrophilic colloid binder and is coated on a support.

3 A heat processable radiant-energy-sensitive imageforming layer of claim 1 containing a mixture of two different heat-sensitive salt compounds selected from those having the formula:

such that the compounds have identical anions and different cations.

4. A thermographic element comprising a support coated with a thermographic layer comprising a hydrophilic binder having dispersed therein:

(1) a heterocyclic quaternary salt selected from those having the formula:

wherein D represents the nonmetallic atoms necessary to complete a ring selected from the class consisting of a heterocyclic ring and a carbocyclic ring, Q represents a group selected from the class consisting of a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom and a (CH)= group, p represents an integer from 1 to 2, R represents a group selected from the class consisting of an alkyl group having from 1 to 18 carbon atoms and an aryl group, R represents a group selected from the class consisting of an alkyl group having from 1 to 18 carbon atoms and an aralkyl group, J represents an anion selected from the class consisting of a p-toluene sulfonate iron, a lower alkylsulfonate ion and a chloroacetate ion;

(2) a compound selected from the class consisting of a p-quinone having at least one unsubstituted hydrogen atom on the ring and a cupric salt; and (3) a heat-sensitive salt compound of a readily decarboxylatable organic acid, said salt compound being selected from those having the formula:

wherein WI-I+ represents a member selected from the class consisting of:

radical and (NH C=NHH+ radical in which L represents the nonmetallic atoms necessary to complete a cyclic structure selected from the class consisting of piperidine, Z-alkyl substituted piperidine, picoline, 2-alkyl substituted pyridine, and morpholine; R represents a member selected from the class consisting of a hydrogen atom, a lower alkyl radical having from 1 'to 4 carbon atoms; d is an integar of from 1 to 2; X represents a member selected from the class consisting of a hydroxyl radical, and an --NR radical; R represents a member selected from the class consisting of a hydrogen atom, an alkyl radical having from 1 to 8 carbon atoms, an aminoalkyl radical having from 1 to 6 carbon atoms; R represents a member selected from the class consisting of a 1,3-dihydroxy-Z-hydroxymethyl-2-propyl radical and an aminoalkyl radical having from 1 to 6 carbon atoms; n is an integer of from 1 to 3; Y represents a member selected from the class consisting of a hydrogen atom, a chlorine atom, a bromine atom, and a fluorine atom; m is an integer of from 1 to 4; and Z represents a member selected from the class consisting of a ing upon heating to release a free amine selected from the class consisting of those having the formulas:

5. A radiation-sensitive image-forming element designed for photothermography and for thermophotography comprising a support coated with a radiation-sensitive image-forming layer comprising a hydrophilic binder having dispersed therein:

(1) a light-sensitive diazonium compound,

(2) a diazo coupler compound, and

(3) a heat-sensitive salt compound of a readily decarboxylate organic acid, said salt compound being selected from those having the formula:

l WH+O- (CYz) m-1 -Z wherein WH represents a member selected from the class consisting of 1 radical and (NH C:NHH+ radical in which L represents the nonmetallic atoms necessary to complete a cyclic structure selected from the class consisting of piperidine, 2-alkyl substituted piperidine, picoline, 2-alkyl substituted pyridine, and morpholine; R represents a member selected from the class consisting of a hydrogen atom, a lower alkyl radical having from 1 to 4 carbon atoms; d is an integer of from 1 to 2; X represents a member selected from the class consisting of a hydroxyl radical, and an NR radical; R represents a member selected from the class consisting of a hydrogen atom, an alkyl radical having from 1 to 8 carbon atoms, an aminoalkyl radical having from 1 to 6 carbon atoms, R represents a member selected from the class consisting of a 1,3- dihydroxy-Z-hydroXymethyl-2-propyl radical and an aminoalkyl radical having from 1 to 6 carbon atoms; n is an integer of from 1 to 3; Y represents a member selected from the class consisting of a hydrogen atom, a chlorine atom, a bromine atom, and a fluorine atom; m is an integer of from 1 to 4; and Z represents a member selected from the class consisting of a o CH i radical, a Cl C-- radical, a BC radical, a 1 0-- radical, a Br C-- radical, a NEC radical, and a (NO C- radical, such that when Z is a u CH3C radical, m is the integer 2 and Y is a hydrogen atom, said organic acid moiety of said salt compound decarboxylating upon heating to release a free amine selected from the class consisting of those having the formulas:

6. A thermographic element comprising a support and a thermographic layer said layer consisting of poly(vinylbutal) 2,3-dirnethylbenzothiazolium-p-toluenesulfonate, pquinone and guanidinium trichloroacetate, which upon exposure of said heat-sensitive element to radiant energy in heat conductive association with an image pattern containing portions highly absorptive of said radiant energy and portions substantially nonabsorptive of said radiant energy, said heat-sensitive layer undergoes a rapid color change only in those areas in heat conductive association with those areas highly absorptive of said radiant energy.

7. A thermographic element comprising a support and a thermographic layer, said layer consisting of ethyl cellulose, 3-ethyl-2-methylbenzothiazolium p-toluenesulfonate, cupric chloride dihydrate and guanidinium trichloroacetate which, upon exposure of said heat-sensitive element to radiant energy in heat-conductive association with an image pattern containing portions substantially nonabsorptive of said radiant energy, said heat-sensitive layer undergoes a rapid color change only in those areas in heatconductive association with those areas highly absorptive of radiant energy.

8. A photothermographic element comprising a support and a photothermographic layer, said layer consisting of poly(vinylbutal), 4-diethylaminobenzenediazonium chloride zinc chloride, 2,3-dihydroxynaphthalene and morpholinium trichloroaeetate, which upon exposure through an original image with light followed by heat treatment, produces a positive azo dye image of the original.

9. A thermophotographic element comprising a support and a thermophotographic layer consisting of poly(vinylbutal), the photodecomposable component 4-diethylaminobenzenediazonium chloride, 2,3-dihydroxynaphthalene and the decarboxylatable compound guanidinium trichloroacetate which upon exposure to radiant energy in heat conductive association with an image pattern containing portions highly absorptive of said radiant energy and portions substantially nonabsorptive of said radiant energy, said thermophotographic layer undergoes a rapid color change only in those areas in heat conductive association with those areas highly absorptive of said radiant energy.

10. A light-sensitive photographic element comprising a support and a light-sensitive silver halide emulsion layer containing a heat-sensitive decarboxylatable compound selected from the class consisting of those having the formula:

l rrl I-to c (CY2)(m'1) in which X represents a member selected from the class consisting of hydroxyl radicals and NR radicals, R represents a member selected from the class consisting of a hydrogen atom and lower alkyl radicals having from 1 to 4 canbon atoms, Y represents a member selected from the class consisting of a hydrogen atom, a chlorine atom, a bromine atom and a fluorine atom, m is a positive integer of from i to 4 and Z represents a member selected from the class consisting of CH CO- radicals, Cl C-- radicals, F C radicals, I C radicals, Br C- radicals, NC- radicals and (NO C radicals such that when Z is a CH CO radical, m is the integer 2 and Y is a hydrogen atom, said light-sensitive element upon exposure to a light image is developable by treating the exposed light-sensitive layer with steam which causes the said decal-boxylatable compound to decarboxylate to produce a product having the formula:

said product developing the exposed silver halide to a silver image.

11. A light-sensitive photographic element comprising a support and a light-sensitive silver bromide emulsion layer containing p-aminophenol trichloroacetate which after exposure through a negative image to light from an incandescent light source is developed by treating the exposed light-sensitive layer with steam to produce a positive silver image.

NORMAN G. TORCHIN, Primary Examiner.

MILTON STERMAN, Examiner.

22 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,220,86 Dated November. 3Q 1965 Inventor(s) John F. Tinker and John J. Sagura It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 13 line 17 delete the expression "integer" and substitute in its place ----integer---; and line 60 delete the expression "carboxylate" and substitute in its place --carboxylatable---.

Column l linfis 33-39 the structure reading should read NH SIGNED RND SEALED MAY 5 197 (SEAL) Attest:

Edward M. Fletcher, It. WILLIAM E. SOHUYLER m. Attesting Offi Commissioner of Patents 

1. A HEAT PROCESSABLE RADIANT-ENERGY SENSITIVE IMAGEFORMING LAYER CONTAINING: (A) A HEAT-SENSITIVE SALT COMPOUND OF A READILY DECARBOXYLATABLE COMPOUND BEING SELECTED FROM THOSE HAVING THE FORMULA:
 4. A THERMOGRAPHIC ELEMENT COMPRISING A SUPPORT COATED WITH A THERMOGRAPHIC LAYER COMPRISING A HYDROPHILIC BINDER HAVING DISPERSED THEREIN: (1) A HETEROCYCLIC QUATERNARY SALT SELECTED FROM THOSE HAVING THE FORMULA: 